21
HPCC Team 21 Observations Computational intensive applications with fine-tuned floating-point operations have less chance to be improved in performance from Hyper-Threading, because the CPU resources could already be highly utilized Cache-friendly applications might suffer from Hyper-Threading enabled, because processes running on logical processors might be competing for the shared cache access, which might result in performance degradation Communication-bound or I/O-bound parallel applications may benefit from Hyper-Threading, if the communication and computation can be performed in an interleaving fashion between processes. The current version of Linux OSs support on Hyper-Threading is limited, which could cause performance degradation significantly if Hyper-Threading is not applied properly. To the OS, the logical CPUs are almost undistinguishable from physical CPUs The current Linux scheduler treats each logical CPU as a separate physical CPU - which does not maximize multiprocessing performance A patch for better HT support is available (Source: "fully HT-aware scheduler" support – 2.5.31-BK-curr, by Ingo Molnar)